In vitro susceptibility of quinolone-resistant Enterobacteriaceae uropathogens to fosfomycin trometamol, in Dakar, Senegal

We conducted a study in order to confirm the eligibility of fosfomycin trometamol as an alternative treatment to quinolones for urinary tract infections. Among 102 quinolone-resistant Enterobacteriaceae strains, resistance rates to first line-prescribed antibiotics were above 77%. The resistance rate to fosfomycin was 2%.

Analysis of topoisomerase mutations in fluoroquinolone-resistant and -susceptible Campylobacter jejuni strains isolated in Senegal

In this study, topoisomerase mutations in ciprofloxacin-resistant and -susceptible Campylobacter jejuni were analysed by DNA sequencing. In certain ciprofloxacin-resistant C. jejuni, the mechanism of resistance was complex. The Thr86-Ala substitution in the GyrA protein appears to play a role in increasing the minimum inhibitory concentration of nalidixic acid only. In addition, isolates with this amino acid change and those resistant to quinolones but lacking a mutation in the GyrA quinolone resistance-determining region could be derived from two different clones. Based on gyrA and gyrB polymorphisms, C. jejuni isolates from the Dakar region of Senegal appeared to be less diverse than those from other countries. Moreover, C. jejuni isolates in Senegal appeared to differ from European isolates by lack of a silent mutation at codon 120 of the gyrA gene.

Performance evaluation of automated depolarization analysis for detecting clinically unsuspected malaria in endemic countries

This prospective study evaluated the efficiency of automated depolarization analysis for recognition of unsuspected malaria by haemozoin detection during routine full blood count (FBC) screening of 676 randomly selected out-patients in a malaria hypoendemic area of Senegal. An additional 123 patients with clinically suspected malaria were studied for comparison. Of the 799 samples, 648 (81.1%) were categorized as malaria-negative, 83 (10.4%) as malaria-positive, and 68 as treated (early convalescence) or subclinical malaria (indirect evidence of infection). At a discrimination level of one or more atypical pigment-containing monocytes (PCM), negative and positive agreement was found to be 95.6% and 91.6% respectively for all malaria-negative and parasite-positive samples combined. Increasing the discriminator to two or more PCM events improved the overall agreement to 97.5%. Multivariate analysis showed that the only significant risk factor for the presence of PCM (odds ratio>200) was malaria infection. In the randomly selected group of 676 patients, 41 unsuspected cases of malaria infection were detected using the panel of reference diagnostic tests, and 37 (90.2%) of these had atypical PCM. The detection of clinically unrecognized malaria infection as part of a routine FBC procedure is a potentially useful extended application for laboratories in countries with endemic malaria.

[Evaluation of E-test method in determination of susceptibility of Mycobacterium tuberculosis to four antituberculosis drugs]

The objective of this study is to evaluate the performance of E-test method versus the standard proportion method, by testing susceptibility of Mycobacterium tuberculosis to four antituberculosis drugs: rifampicin, isoniazid, streptomycin, and ethambutol. Thirty strains isolated at Medical Biology Laboratory of Pasteur Institute of Dakar were tested. The strains were identified by morphological, cultural and biochemical characteristics (microscopy, time of growth, type of colonies, catalase, niacin-test). H37RV strain was tested as reference strain. The E-test method was performed on 7H11 agar with OADC, and the standard proportion method was performed on Lowenstein-Jensen agar. With results of these tests, the authors determined the E-test sensitivity and specificity, and the positive and negative predictive values (PPV, NPV). E-test method gave correct results from the eighth day, with stability of the zone of inhibition until the 21st day. The E-test method has 73% of sensibility and 100% of specificity, with 100% of PPV and 78% of NPV for streptomycin. For isoniazid, these results are respectively: 16.6%, 100%, 100% and 82.7%. There was found a good correlation between the two methods.

Fluoroquinolone Susceptibility of Campylobacter Strains, Senegal

To assess fluoroquinolone susceptibility of Campylobacter strains in Senegal, skin samples were collected from 250 chicken carcasses from January 2001 to October 2002. Among 205 isolated Campylobacter strains, 59% and 41% were identified as Campylobacter jejuni and C. coli, respectively; the overall ciprofloxacin-resistance rate was 34%.

Evaluation of the seroprevalence of rubella in the region of Dakar (Senegal)

Data on the seroepidemiology of rubella in tropical African countries are still scarce. To determine the seroprevalence in Senegal, we conducted a 6 year retrospective survey among women of child bearing age in the urban region of Dakar, Senegal. The global seroprevalence determined with a commercial enzyme immunoassay among 3471 serological results was 90.1%. The distribution of this prevalence appeared stable with no significant difference between the years of study, age groups, and the socio-economic level of the districts of residence of the patients. Compared to seroepidemiological surveys performed in other western African countries, our data suggest an important and stable circulation of the virus in the region of Dakar. The lack of data on rubella and congenital rubella syndrome (CRS) in Senegal should encourage medical authorities to establish a national rubella surveillance network in order to develop a strategy to survey and control CRS in the country.

[Vibrio cholerae in Madagascar: study of a multiresistant strain]

Madagascar was cholera free until March 1999. The first case was reported in Mahajanga, a north west coast harbor. Ten months later and despite a massive use of tetracycline as prophylactic drug, cholera had reached every region of the island. All suspected cholera samples were analysed at the Pasteur Institute of Madagascar where susceptibility to tetracycline was systematically performed. On February 2000, a multidrug resistant strain of V. cholerae was isolated. We studied this strain by performing Minimal Inhibitory Concentration (MIC) and by plasmidic and conjugative assay. As the original strain, this multiresistant V. cholerae showed a resistance to cotrimoxazole, to streptomycin and chloramphenicol but, in addition to, appeared strongly resistant to ampicillin and tetracycline. This strain harboured a 26 kb self-transmissible plasmid. Conjugation tests showed the possibility of plasmidic segregates or acquisition of two different plasmids. The weak transfer rate could explain why we have isolated only one multiresistant strain. The emergence of a such multiresistant strain should encourage the medical authorities to reinforce the epidemic survey in every medical Malagasy district and to carry out new antimicrobial surveys to describe the mechanisms of the spread of these resistances.

[Avidity of IgG anti-Toxoplasma gondii. Study to establish a new decision tree for screening]

Toxoplasmosis infection is commonly asymptomatic, but it may have severe teratogenic consequences. The authors review the literature on serologic screening in the first trimester of pregnancy.

[Seroprevalence of rubella in pregnant women at Antananarivo. Study of 853 sera at the Pasteur Institute in Madagascar]

The authors reported the results of a seroepidemiological study of rubella in pregnancy in Antananarivo at the Institut Pasteur de Madagascar. A total of 853 sera were tested using hemagglutination inhibition as reference method. Rubella antibodies were present in 80.5% of the malagasy pregnant women. These results seem quite similar to those observed from other tropical african countries. The rubella prevalences among the pregnant woman's population coming from France, India and Pakistan and living in Antananarivo (respectively, 89.8% and 81.8%) seem the same than in their home countries.

Distribution and susceptibility of bacterial urinary tract infections in Dakar, Senegal

To assess the current distribution and antibiotic susceptibility patterns of uropathogens isolated from community-acquired urinary tract infections (UTIs) in Dakar, a retrospective study was carried out at the biomedical laboratory of Institut Pasteur de Dakar between January 1999 and December 2000. The most important finding, among Enterobacteriaceae, was the emergence of multidrug resistant strains (extended-spectrum beta-lactamase and both chromosomally derepressed and plasmid mediated cephalosporinase producing strains) affecting 2.9% of all Enterobacteriaceae. Of Gram-positive cocci, 15% of Staphylococcus aureus were methicillin-resistant. Our data show the original distribution of uropathogens from UTIs in ambulant patients and the emergence of multidrug resistant strains in Dakar.

[Non-tubercular bacterial meningitis in children in Antananarivo, Madagascar]

OBJECTIVE

To determine the bacterial causal agents of meningitis and their pattern of resistance, in children more than one month to 14 years of age.

METHODS

A 2 years, prospective study (June 1998 to June 2000) on bacterial meningitis in children was carried out in the main hospitals in Antananarivo. The enrollment criteria upon admission were fever with symptoms of meningitis and/or convulsions and/or coma. A lumbar puncture was systematically performed in each child. The aspect of the cerebrospinal fluid was described, the level of protein and glucose estimated, soluble antigens measured. Following the examination of a Gram straining, an aliquot of the fluid was cultured on specific medium. Antimicrobial sensitivity testing of isolated pathogens was performed.

RESULTS

Bacterial meningitis was confirmed in 119 children: 95 (80%) and 111 (93%) were less than 12 and 24 months of age, respectively. The sex distribution was 1:1. Three predominant microorganisms were identified: Streptococcus pneumoniae (45%), Haemophilus influenzae b (43%) and Neisseria meningitidis (10%) of which ten of 12 cases were belonging to serogroup B. The other microorganisms isolated were E. coli (2%). S. pneumoniae were found to be sensitive to penicillin G and H. influenzae were found to be sensitive to the third generation cephalosporins. Seven percent of the S. pneumoniae strains were mildly resistant (R + I) to chloramphenicol and between 29 and 50% to aminoglucosides. A moderate resistance against gentamicin and amoxicillin was found in 22-29% of the H. influenzae strains. The mortality rate was high (31%) and among the surviving children 30% presented with neurosensitive disorders.

CONCLUSION

According to these data we may recommend the inclusion of vaccination against H. influenzae in the children immunization program in Madagascar. The early diagnosis and treatment with appropriate antibiotics, such as third generation of cephalosporins, are other critical measures to be taken in order to reduce the risk of developing severe complications associated to bacterial meningitis.

Chromobacterium violaceum: a case of diarrhea in Senegal

A 5-year-old infant with diarrhea had heavy growth of Chromobacterium violaceum cultured from stool. This organism is restricted geographically between latitudes 35 degrees N and 35 degrees S. It can cause sepsis and various focal infections but is not a well-known cause of diarrhea.

[Estimation of normal hemogram values in Madagascar]

In Madagascar, as in several african countries, haematological normal values has not been established. To assess the haematological normal values in the laboratory of the Institut Pasteur de Madagascar, blood cell counts among 67 adults healthy malagasy volunteers, living in highlands of Madagascar, was performed. Blood was analysed with a Coulter STKS haematological autoanalyzer. A significant difference was noted between both sexes for the count of red blood cells, leukocytes, platelets, neutrophile polynuclears, eosinophile polynuclears, lymphocytes and for haemoglobin and haematocrit values. Our data were compared to those of different african and caucasian populations.

[Update on plague in Madagascar]

After a thirty year period of successful control, bubonic plague showed the first signs of return in Madagascar where a fatal outbreak occurred in Antananarivo in 1978. A second outbreak was observed in Mahajanga in 1991 after more than a half century. In 1997, 459 confirmed or presumptive cases were reported, as compared to 150 to 250 cases during the last years. However the actual extent of this recrudescence must be placed in the perspective of a more efficient control program that has led to better reporting of suspected cases and availability of more accurate diagnostic techniques. Recent research has led to the development of highly effective immunological diagnostic tools (detection of antibodies and F1 antigen) allowing not only better surveillance of the disease in man and animals but also renewed study of the epidemiological cycle in the current environment. In this regard the capacity of several endemic fleas as vectors and the role of the rat Rattus norvegicus and the musk shrew Suncus murinus are currently under investigation. Genetic study of strains collected from 1936 to 1996 has demonstrated the appearance of 3 new ribotypes of Yersinia pestis since 1982 in the zones of strongest plague activity in Madagascar. A strain showing multiresistance to standard therapeutic antibiotic agents was isolated in 1995. Bubonic plaque is a priority health problem in Madagascar but remains a major concern for the rest of the world.

[660 cases of histologic extra-pulmonary tuberculosis at the Pasteur Institute in Madagascar]

A 33 months retrospective study (from September 1992 to May 1995) of 8525 patients indicated that the incidence of histologic extrapulmonary tuberculosis (EPT) was 7,7%. The 8341 malagasy native patients presented an incidence of 7.8%. Male are more frequently infected than female. Most samples came from Antananarivo, with a prevalence reaching 12,5% while it was only 2,9% in the provinces. Most pathologic EPT were pleural tuberculosis (55,6%) and ganglial tuberculosis (34%). Peritoneal tuberculosis were much less frequent. According to literature data in Madagascar, the incidence of histologic EPT is obviously increasing.